Hundreds of parents piling into the parking lot creates gridlock. “My mom is here. She is over there somewhere stuck in traffic,” says sophomore Alex Newman.

In the end, police don’t find the threat.

But students find their last day of school at once confusing and exhilarating.

“Wow, there’s people with guns in my school,” says Newman, of what he calls a once-in-a-lifetime experience.

Parents are grateful it ended as it did.

“I am relieved no one was hurt. We’ve had our share of tragedies in Colorado,” says Luepke.

It turns out a student’s history project included a replica of a rifle. Here’s the details in a statement from Thornton Police:

“At approximately 12:49 pm, a parent called Thornton Police Dispatch and stated that she had picked up a school project from her son at Thornton High School earlier today that involved a replica rifle.”

“Investigators responded and took possession of the display. The student was subsequently interviewed and stated that he had brought in a history class project to school on Wednesday, May 22, that involved a memorial display involving a ‘Fallen Soldier Battle Cross.'”

“The display involved a rifle, helmet and boots. He stated that his mom had responded to the school earlier today and picked up his class project. He stated that he had carried it out of the school and to his awaiting mother in the parking lot. The rifle utilized in this display was a replica AK-47,” the Thornton Police statement concluded.